Saving and Reading Metadata in Adobe Photoshop Lightroom 2

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Saving and reading metadata

Article Description

Lightroom is built around the principle that the imported images are the master negatives: Lightroom records the changes made as metadata information and these edit changes are initially stored at a central location in the Lightroom catalog. In this excerpt, Martin Evening talks about saving, reading and tracking metadata in Lightroom 2.

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Saving and reading metadata

Another pain point for newcomers to Lightroom has been the question of the best way to save images. In our very first computer
lesson we all learned how important it is to always save your work before you close down a program. Some Lightroom users have
been confused by the fact that there is no “save” menu item and left wondering if they would lose all their work after they
quit Lightroom. Of course you realize soon after using the program that all work is saved automatically. Even if Lightroom
suffers a crash or there is a power failure, you should never lose any of your data.

It is important to remember that as you carry out any kind of work in Lightroom—whether you are adjusting the Develop settings,
applying a color label or star rating, or editing keywords or other metadata—these edits are initially all stored in a central
Lightroom catalog on your hard disk. For simplicity’s sake we can summarize these by grouping them under the term “metadata
edits.” Whenever you alter a photo in Lightroom, you are not recording anything in the actual image file. Lightroom is built
around the principle that the imported images are the master negatives: Lightroom records the changes made as metadata information
and these edit changes are initially stored at a central location in the Lightroom catalog. This is why Lightroom is so much
faster at searching images compared to a browser program like Bridge. You can add, search, and read metadata information much
more quickly, because the metadata information is stored in an easy-to-access database. However, it is possible to have the
metadata information stored in both the database and the individual picture files. In the case of JPEG, TIFF, PSD, or DNG
images, there is a dedicated XMP space within the file’s header that can be used to store the metadata. While with proprietary
raw files, it has to be stored separately in what is known as an XMP sidecar file.

If you work on an image in the Lightroom catalog using another program such as Photoshop or Bridge and you make any changes
to the metadata, these edit changes will always be made to the file itself. When such an image is opened up via Lightroom
again we can find ourselves having to decide whether the “truth is in the database” (the Lightroom catalog database) or the
“truth is in the file.”

TIP

Saving metadata to the file can be seen as a good thing to do because it adds an extra level of security and allows the metadata
entered via Lightroom to be shared when viewed in other programs. But this security does come at a cost. The good thing about
having all the metadata information stored in a single database file is that it is lightweight. When it comes to backing up
data to another hard drive, the backup process can take just a minute or so, even for a large catalog, to copy from one drive
to another. When you export the metadata to the files, this means that once a file has been modified, the whole file has to
be backed up. This means that all DNG, TIFF, PSD, and JPEG files will have to be copied as complete files during the backup
process and what would otherwise take a minute starts taking hours to process. Interestingly, you could argue that there is
an advantage here if raw files are not converted to DNG since backing up the .xmp sidecar files is a lot quicker than backing
up the DNGs where the XMP metadata is embedded.

Saving metadata to the file

For all the time that you are working in Lightroom it should not really matter if the metadata information is stored only
in the central database. Of course it feels kind of risky to trust everything to a single database file, but that is why there
is a built-in database backup feature in Lightroom as well as a diagnostics and a self-repair function (see Figure 4.67) to help keep your database file protected. Plus I highly recommend that you back up your data regularly anyway. Despite
all that, it is still important to save the metadata edits to the files so that the “truth is in both the database and the
file.” By doing this you can maintain better compatibility between the work you do in Lightroom and the work you do using
external programs.

So what is the best way to save metadata to the files? If you go to the File menu and choose Catalog Settings, you will see
the dialog shown in Figure 4.68, where there is an option called “Automatically write changes into XMP.” In the previous version of this book I recommended
you keep this option switched off because it could slow down the Lightroom program. However, since the version 1.3 update,
it has been OK to leave this switched on because Lightroom will now only automatically write to the files’ XMP space when
it is convenient to do so, without affecting the program’s performance. Checking this option will ensure that all the files
in the Lightroom catalog will eventually get updated. However, if you want to be sure that a file’s XMP space gets updated
right away or you have “Automatically write changes into XMP” switched off, then you can use the Metadata Save Metadata to Files command (or Photo Save Metadata to Files, if working in the Develop module). This forces an immediate export of the metadata information from
the Lightroom internal catalog to the image file’s XMP space. In practice I’d recommended using the (Mac), (PC) shortcut anyway every time you wish to export and update the metadata to a photo or a group of selected photos.

Tracking metadata changes

In order to keep track of which files have been updated and which have not, Lightroom does offer some visual clues. If you
go to the View menu and open the View Options dialog, there is a check box in the Cell Icons section called Unsaved Metadata.
When this is checked you may see a “calculating metadata” icon () in the top-right corner of the grid cells as Lightroom scans the photos in the catalog, checking to see if the metadata
is in need of an update. You will also see this when Lightroom is in the process of saving or reading metadata from a file.
If the metadata in the catalog and the file are in sync, the icon will disappear. If there is a “metadata status conflict”
you will see either a down arrow (Figure 4.69) or an up arrow (Figure 4.70). The down arrow indicates that the metadata information embedded in the photo’s XMP space is now out of date compared to
the current Lightroom catalog file and that now would be a good time to choose Metadata Save Metadata to File ([Mac], [PC]). Figure 4.71 shows the Library View Options dialog with the Unsaved Metadata option circled.

In the Metadata panel (Figure 4.72) is an item called Metadata Status, which will say “Has been changed” if anything has been done to edit the photo metadata
settings since the last time the metadata was saved to the file. This is basically telling you the same thing as the metadata
status icon that appears in the Library grid cells.

Choosing Save Metadata to File will make the metadata status icon in the Library grid cells disappear, but if you are uncertain
what to do you can click the icon in the grid to open the dialog shown in Figure 4.73. This dialog asks if you want to save the changes to disk (better described as “do you wish to confirm saving the metadata
changes to the photo’s XMP space?”).

The up arrow shown in Figure 4.70 indicates that the metadata information embedded in the image file’s XMP space is out of sync and more recent than the current
Lightroom catalog file. This will most likely occur when you have edited a Lightroom catalog file in Camera Raw and the externally
edited image has a more recently modified XMP than the Lightroom catalog. To resolve this choose Metadata Read Metadata from file.

The other possibility is that a Lightroom catalog photo may have been modified in Lightroom (without saving the metadata to
the file) and also been edited by an external program, resulting in two possible “truths” for the file. Is the truth now in
the Lightroom catalog, or is the truth in the externally edited file XMP metadata? If you see the icon shown in Figure 4.74, click to open the dialog in Figure 4.75 where you can either choose Import Settings from Disk if you think the external settings are right, or choose Overwrite Settings
if you think the Lightroom catalog settings are the most up to date.

XMP read/write options

Let’s now take a closer look at what this XMP settings business is all about. The XMP space is the hidden space in a document
such as a JPEG, TIFF, PSD, or DNG file that is used to write the metadata settings to. In the case of proprietary raw files
it would be unsafe for Lightroom to write to the internal file header, so .xmp sidecar files are used instead to store the
XMP metadata. The XMP metadata includes everything that is applied in Lightroom, such as the IPTC information, keywords, file
ratings, flags, and color labels, as well as the Develop settings that are applied via Quick Develop or the Develop module.

In the Metadata section of the Catalog Settings (Figure 4.68), the “Include Develop settings in metadata inside JPEG, TIFF and PSD files” option lets Lightroom distinguish between writing
the Develop settings metadata to the XMP space for all files including JPEGs, TIFFs, and PSDs, or to raw and DNG files only.
This is a preference that predetermines what gets written to the XMP space when you make an explicit command to save the file
metadata out to a file. The ability to save Develop settings with the file can be a mixed blessing. If you are sharing images
that are exported from Lightroom as individual images (or as an exported catalog) with another Lightroom user, you will most
definitely want to share the Develop settings for all the images that are in the catalog. But if you are sharing files from
Lightroom with Bridge CS3 or later, this can lead to some unexpected file behavior when you open non-raw files via Bridge.
Basically what will happen is that raw and DNG images that have had their Develop settings modified via Lightroom will open
via Camera Raw in Bridge exactly as you expect to see them, since Bridge is able to read the settings that were created in
Lightroom. However, where you have non-raw files such as JPEGs, TIFFs, or PSDs that have been edited using the Develop settings
in Lightroom, and the Develop settings have been written to the file’s XMP space, Bridge may now consider such files to be
like raw files and open them up via Camera Raw rather than open them directly in Photoshop. That’s what I mean by mixed blessings.
If you want Lightroom to retain the ability to modify the XMP space of non-raw files for data such as file ratings, keywords,
and labels but exclude storing the Develop settings, you should uncheck the “Include Develop settings in metadata inside JPEG,
TIFF and PSD files” option. Do this and the Lightroom Develop settings for non-raw files will only get written to the catalog
and they won’t get exported to the files when you choose Save Metadata. But raw and DNG files will be handled as expected.
On the plus side, you will never be faced with the confusion of seeing your non-raw images such as JPEGs unexpectedly default to open via Camera Raw when you try to open them up in Photoshop CS3 or later. The downside
is that if you modify a non-raw image in Lightroom using Develop, these changes will only be seen in Lightroom and not by
Bridge. For these reasons, my advice is to turn off “Include Develop settings in metadata inside JPEG, TIFF and PSD files.”
To help explain the settings and how they affect image files after being modified in Lightroom, I have summarized how these
options affect the way different file formats will be handled. Please note that these steps do assume that you are using Photoshop
CS3 with Bridge CS3 (or later) and have updated Camera Raw to version 4.1 or later.

If a photo in Lightroom is modified using the settings shown here with “Automatically write changes into XMP” and “Include
Develop settings in metadata inside JPEG, TIFF and PSD files” switched on, then all the adjustments that are made to the image
will automatically be saved to the Lightroom catalog and also saved to the original image file. In the case of proprietary
raw files, the XMP metadata will be written to an XMP sidecar file and when opened via Bridge, will (as you would expect)
open via the Camera Raw dialog with the same Develop settings that were applied in Lightroom. In the case of DNG files, the
XMP metadata will be written internally to the file and these too will open in Camera Raw. In the case of JPEG, TIFF, and
PSD files, because you are including the Lightroom Develop settings in the export to the XMP space, they will default to opening
in Bridge via the Adobe Camera Raw dialog.

If the “Automatically write changes into XMP” option is disabled, the metadata edits will now only be saved to the Lightroom
catalog. If you were to open a JPEG, TIFF, or PSD image from Bridge that had been edited in Lightroom, it will open directly
in Photoshop and not open via the Camera Raw dialog. But at the same time, any image ratings, metadata keywords, or other
information that have been entered while working in Lightroom will not be visible to Bridge or any other external editing
program (this assumes that you are not manually saving the metadata to the file, as described in the following paragraph).

In this example, the “Include Develop settings in metadata inside JPEG, TIFF and PSD files” option is still switched on, so
if you did want the metadata edits to be saved to the files’ XMP metadata space, you would have to do so manually using a
Save Metadata command ([Mac], [PC]). But in doing so, the problem with a Save Metadata command is that you would again be saving all the Lightroom settings
to the files’ metadata space (including the Develop settings) and we are back to the same scenario as in Step 1 where non-raw
files may default to opening via Camera Raw, which is perhaps not what the customer wanted!

Now let’s look at what happens when “Include Develop settings in metadata inside JPEG, TIFF and PSD files” is disabled and
“Automatically write changes into XMP” is switched on. Any edits made in Lightroom will automatically get saved to the Lightroom
catalog as well as to the files’ XMP metadata space—all the settings, that is, except for the Develop settings, which will
be saved to the proprietary raw and DNG files, but not to the JPEG, TIFF, or PSD files.

In this scenario, all metadata information will be saved to all types of files (with the exception of the Develop settings
not being written to JPEG, TIFF, or PSD files that have been edited in Lightroom). Proprietary raw and DNG files that have
been edited in Lightroom will preserve their appearance when viewed in Bridge, and will open as expected via the Bridge Camera
Raw dialog. But with JPEG, TIFF, or PSD files the Develop settings won’t be transferred and because of this they will open
from Bridge directly into Photoshop without opening via the Camera Raw dialog. The downside is that such images may not always
look the same in other programs as they did in Lightroom. It all depends on whether you want to use the Develop module to
modify the JPEG, TIFF, or PSD images as you would do with the raw images. Overall this is probably the most useful configuration
to use, because it preserves the informational metadata in non-raw files that have been modified in Lightroom and avoids non-raw
files opening up via the Camera Raw dialog.